CHAPTER XXX. 
OPHIOGLOSSALES. 
e 
THE Ophioglossales include three! genera of living plants: Ophzoglossum, 
with ten species as described in Hooker's Synopsis Filicum, though 
Prantl distinguishes twenty-nine: Botrychium with about six, or according 
to Prantl fifteen species: and Ae/minthostachys with only one. The three 
genera have well-marked characters in common, so that there is no doubt 
of their natural affinity. The most distinctive is the fertile spike, a 
process which rises from the adaxial surface of the leaf, and serves as 
a basis for insertion of the sporangia: these are of the eusporangiate 
type, and are without any annulus. There is no early fossil that 
can be attributed with any certainty to this family, and thus, notwith- 
standing that the appearance of these plants is commonly held to 
be archaic, there is no direct evidence of any great antiquity. They 
have usually been cld$sed with the Ferns, of which thay have been 
held to be an outlying group. Other authors recognise certain 
characters as linking them with the Lycopodiales. A careful consider- 
ation: of the evidence leads to the conclusion that they are best in 
place as an independent phylum of the Ophioglossales, and the justifi- 
cation of this will appear from the account of them now to be given. 
Any decision on the point of affinity is closely related to the 
question whether the organisms constitute an upgrade or a downgrade 
sequence. In the description which follows the various types of the 
family will be traced from the simpler to the more complex, and the 
discussion of their relationships will be left over to the conclusion, 
when the facts necessary for forming an opinion shall be before the 
reader. 
!The foundation of a fourth genus ‘‘ Sceptridium” has been suggested by H. L. Lyon 
(Bot. Gaz., Dec., 1905). It is based mainly upon embryological detail. I prefer for the 
present to suspend any decision as to the validity of this proposal, awaiting the detailed 
statement of the facts. 
